Core network selection method, apparatus, and system

ABSTRACT

Embodiments provide a core network selection method, an apparatus, and a system. The method includes the following steps: obtaining first dedicated core network (DCN) information from an access network device, where the first DCN information includes information about at least one DCN that can be accessed by the access network device. The method also includes selecting a to-be-accessed DCN from the at least one DCN according to the first DCN information, and sending information about the to-be-accessed DCN to the access network device, so that the access network device determines a core network device according to the information about the to-be-accessed DCN.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/760,897, filed on Mar. 16, 2018, which is a National Stage ofInternational Application No. PCT/CN2015/089929, filed on Sep. 18, 2015.All of the aforementioned patent applications are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

Embodiments of the present invention relate to communicationstechnologies, and in particular, to a core network selection method, anapparatus, and a system.

BACKGROUND

To meet service requirements in different scenarios, a network slicing(Network Slicing) method may be used. That is, multiple network slicesconstitute a network, and a single network slice may be defined as a setof logical network function entities supporting a communications servicerequirement in a specific scenario, for example, a network slicesupporting communication of a large quantity of machine devices or anetwork slice supporting a mobile broadband service. There may bemultiple slicing manners for network slicing. For example, a corenetwork may be sliced, an access network may be sliced, or a corenetwork and an access network may be sliced together. A dedicated corenetwork (Dedicated Core Network, DCN for short) defined in the 3rdGeneration Partnership Project (3rd Generation Partnership Project, 3GPPfor short) is a solution for slicing a core network.

In an existing 3GPP standard solution, a core network device triggers arerouting process of an access network device. When receiving a terminalrequest message sent by the access network device, such as aregistration request or an update location request, a core-networkcontrol function entity may determine whether the core-network controlfunction entity belongs to a specific DCN that serves the access networkdevice. If no, the core-network control function entity sendsinformation about the specific DCN of the access network device, torequest the access network device to reroute the terminal requestmessage to a core-network control function entity in the specific DCN ofthe access network device.

However, in the foregoing solution, the rerouting process of the accessnetwork device requires a large quantity of communication signalinginteractions, increasing a processing delay and decreasing communicationefficiency.

SUMMARY

Embodiments of the present invention provide a core network selectionmethod, an apparatus, and a system, so as to improve accuracy of DCNselection by an access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

According to a first aspect, an embodiment of the present inventionprovides a core network selection method, including:

obtaining first dedicated core network DCN information from an accessnetwork device, where the first DCN information includes informationabout at least one DCN that can be accessed by the access networkdevice;

selecting a to-be-accessed DCN from the at least one DCN according tothe first DCN information; and

sending information about the to-be-accessed DCN to the access networkdevice, so that the access network device determines a core networkdevice according to the information about the to-be-accessed DCN.

With reference to the first aspect, in a first possible implementationof the first aspect, the first DCN information includes a type of the atleast one DCN;

the selecting a to-be-accessed DCN from the at least one DCN accordingto the first DCN information includes:

selecting, from the at least one DCN, a DCN whose type matches a servicetype of user equipment UE, as the to-be-accessed DCN; and

the sending information about the to-be-accessed DCN to the accessnetwork device, so that the access network device determines a corenetwork device according to the information about the to-be-accessed DCNincludes:

sending the type of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the type of the to-be-accessed DCN.

With reference to the first aspect, in a second possible implementationof the first aspect, the first DCN information includes a type, a DCNidentity ID, and a priority of the at least one DCN;

the selecting a to-be-accessed DCN from the at least one DCN accordingto the first DCN information includes:

selecting, from the at least one DCN, one or more DCNs whose types matcha service type of UE; and

when a type of one DCN matches the service type, determining the one DCNas the to-be-accessed DCN; or when types of multiple DCNs match theservice type, selecting the to-be-accessed DCN from the multiple DCNsaccording to the priority; and

the sending information about the to-be-accessed DCN to the accessnetwork device, so that the access network device determines a corenetwork device according to the information about the to-be-accessed DCNincludes:

sending a DCN ID of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the DCN ID of the to-be-accessed DCN.

With reference to any one of the first aspect, or the first or thesecond possible implementation of the first aspect, in a third possibleimplementation of the first aspect, before the obtaining first DCNinformation from an access network device, the method further includes:

sending a first message to the access network device, where the firstmessage is used to indicate a DCN selection capability of the UE; and

the obtaining first DCN information from an access network deviceincludes:

receiving a second message that is sent by the access network deviceaccording to the first message, where the second message includes thefirst DCN information.

With reference to the first aspect, in a fourth possible implementationof the first aspect, the first DCN information includes a type of the atleast one DCN;

the selecting a to-be-accessed DCN from the at least one DCN accordingto the first DCN information includes:

determining a to-be-accessed public land mobile network PLMN accordingto a first preset rule; and

selecting, from at least one DCN supported by the to-be-accessed PLMN, aDCN whose type matches a service type of UE, as the to-be-accessed DCN;and

the sending information about the to-be-accessed DCN to the accessnetwork device, so that the access network device determines a corenetwork device according to the information about the to-be-accessed DCNincludes:

sending the type of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the type of the to-be-accessed DCN.

With reference to the first aspect, in a fifth possible implementationof the first aspect, the first DCN information includes a type of the atleast one DCN;

the selecting a to-be-accessed DCN from the at least one DCN accordingto the first DCN information includes:

selecting, from the at least one DCN, a DCN whose type matches a servicetype of UE, as the to-be-accessed DCN; and

determining a to-be-accessed PLMN according to the type of theto-be-accessed DCN; and

the sending information about the to-be-accessed DCN to the accessnetwork device, so that the access network device determines a corenetwork device according to the information about the to-be-accessed DCNincludes:

sending the type of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the type of the to-be-accessed DCN.

With reference to the first aspect, in a sixth possible implementationof the first aspect, the first DCN information includes a type, a DCNID, and a priority of the at least one DCN;

the selecting a to-be-accessed DCN from the at least one DCN accordingto the first DCN information includes:

determining a to-be-accessed PLMN according to a first preset rule;

selecting, from at least one DCN supported by the to-be-accessed PLMN,one or more DCNs whose types match a service type of UE; and

when a type of one DCN matches the service type, determining the one DCNas the to-be-accessed DCN; or when types of multiple DCNs match theservice type, selecting the to-be-accessed DCN from the multiple DCNsaccording to the priority; and the sending information about theto-be-accessed DCN to the access network device, so that the accessnetwork device determines a core network device according to theinformation about the to-be-accessed DCN includes:

sending a DCN ID of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the DCN ID of the to-be-accessed DCN.

With reference to the first aspect, in a seventh possible implementationof the first aspect, the first DCN information includes a type, a DCNID, and a priority of the at least one DCN;

the selecting a to-be-accessed DCN from the at least one DCN accordingto the first DCN information includes:

selecting, from the at least one DCN, a DCN whose type matches a servicetype of UE;

determining a to-be-accessed PLMN according to the type of the DCN whosetype matches the service type of the UE; and

selecting, according to the priority and from at least one DCN supportedby the to-be-accessed PLMN, a DCN with the highest priority as theto-be-accessed DCN; and

the sending information about the to-be-accessed DCN to the accessnetwork device, so that the access network device determines a corenetwork device according to the information about the to-be-accessed DCNincludes:

sending a DCN ID of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the DCN ID of the to-be-accessed DCN.

With reference to any one of the first aspect, or the fourth to theseventh possible implementations of the first aspect, in an eighthpossible implementation of the first aspect, the obtaining first DCNinformation from an access network device includes:

receiving a third message sent by the access network device, where thethird message includes the first DCN information.

With reference to any one of the fourth to the eighth possibleimplementations of the first aspect, in a ninth possible implementationof the first aspect, before the sending information about theto-be-accessed DCN to the access network device, the method furtherincludes:

requesting, to the access network device, to establish a wirelessconnection.

With reference to any one of the first aspect, or the second to theninth possible implementations of the first aspect, in a tenth possibleimplementation of the first aspect, the selecting a to-be-accessed DCNfrom the at least one DCN according to the first DCN information furtherincludes:

selecting a preset default DCN as the to-be-accessed DCN when the atleast one DCN includes no DCN whose type matches the service type; or

sending an access termination request to the access network device whenthe at least one DCN includes no DCN whose type matches the servicetype; or

obtaining the first DCN information from another access network devicewhen the at least one DCN includes no DCN whose type matches the servicetype.

According to a second aspect, an embodiment of the present inventionprovides a core network selection method, including:

sending first dedicated core network DCN information to user equipmentUE, so that the UE selects a to-be-accessed DCN according to the firstDCN information, where the first DCN information includes informationabout at least one DCN that can be accessed by the access networkdevice;

receiving information about the to-be-accessed DCN sent by the UE; and

determining a core network device according to the information about theto-be-accessed DCN and preconfigured second DCN information, andinitiating a service request to the core network device.

With reference to the second aspect, in a first possible implementationof the second aspect, the information about the to-be-accessed DCNincludes a type of the to-be-accessed DCN; and

the determining a core network device according to the information aboutthe to-be-accessed DCN and preconfigured second DCN informationincludes:

determining, according to the type of the to-be-accessed DCN and thesecond DCN information, a DCN function entity group identifiercorresponding to the type of the to-be-accessed DCN; and

determining the core network device according to the DCN function entitygroup identifier and a second preset rule.

With reference to the first possible implementation of the secondaspect, in a second possible implementation of the second aspect, thedetermining a core network device according to the information about theto-be-accessed DCN and preconfigured second DCN information furtherincludes:

determining a preset default core network device as the core networkdevice when no DCN function entity group identifier corresponding to thetype of the to-be-accessed DCN is determined according to the type ofthe to-be-accessed DCN and the second DCN information; or

sending a fourth message to the UE when no DCN function entity groupidentifier corresponding to the type of the to-be-accessed DCN isdetermined according to the type of the to-be-accessed DCN and thesecond DCN information, where the fourth message is used to terminate anaccess request.

With reference to the second aspect, in a third possible implementationof the second aspect, the information about the to-be-accessed DCNincludes a DCN ID of the to-be-accessed DCN; and

the determining a core network device according to the information aboutthe to-be-accessed DCN and preconfigured DCN information includes:

determining, according to the DCN ID of the to-be-accessed DCN and thesecond DCN information, a DCN function entity group identifiercorresponding to the to-be-accessed DCN; and

determining the core network device according to the DCN function entitygroup identifier and a second preset rule.

With reference to the third possible implementation of the secondaspect, in a fourth possible implementation of the second aspect, thedetermining a core network device according to the information about theto-be-accessed DCN and preconfigured DCN information further includes:

determining a preset default core network device as the core networkdevice when no DCN function entity group identifier corresponding to theDCN ID of the to-be-accessed DCN is determined according to the DCN IDof the to-be-accessed DCN and the second DCN information; or

sending a fourth message to the UE when no DCN function entity groupidentifier corresponding to the DCN ID of the to-be-accessed DCN isdetermined according to the DCN ID of the to-be-accessed DCN and thesecond DCN information, where the fourth message is used to terminate anaccess request.

With reference to any one of the second aspect, or the first to thefourth possible implementations of the second aspect, in a fifthpossible implementation of the second aspect, before the sending firstDCN information to UE, the method further includes:

obtaining the second DCN information from the core network device, wherethe second DCN information includes a type and a DCN function entitygroup identifier of the at least one DCN.

With reference to the fifth possible implementation of the secondaspect, in a sixth possible implementation of the second aspect, thesecond DCN information further includes a DCN ID and a priority of theat least one DCN;

With reference to any one of the second aspect, the first or the secondpossible implementation of the second aspect, or the fifth or the sixthpossible implementation of the second aspect, in a seventh possibleimplementation of the second aspect, before the sending first DCNinformation to UE, the method further includes:

receiving a first message sent by the UE, where the first message isused to indicate a DCN selection capability of the UE; and

the sending first DCN information to UE includes:

sending a second message to the UE according to the first message, wherethe second message includes the first DCN information.

With reference to any one of the second aspect, or the third to thesixth possible implementations of the second aspect, in an eighthpossible implementation of the second aspect, the sending first DCNinformation to UE includes:

sending a third message to the UE, where the third message includes thefirst DCN information.

According to a third aspect, an embodiment of the present inventionprovides a core network selection method, including:

sending second dedicated core network DCN information to an accessnetwork device, so that the access network device determines a corenetwork device according to the second DCN information; and

processing a service request initiated by the access network device.

With reference to the third aspect, in a first possible implementationof the third aspect, the second DCN information includes a type and aDCN function entity group identifier of at least one DCN.

With reference to the first possible implementation of the third aspect,in a second possible implementation of the third aspect, the second DCNinformation further includes a DCN ID and a priority of the at least oneDCN.

According to a fourth aspect, an embodiment of the present inventionprovides user equipment UE, including:

a receiving module, configured to obtain first dedicated core networkDCN information from an access network device, where the first DCNinformation includes information about at least one DCN that can beaccessed by the access network device;

a selection module, configured to select a to-be-accessed DCN from theat least one DCN according to the first DCN information; and

a sending module, configured to send information about theto-be-accessed DCN to the access network device, so that the accessnetwork device determines a core network device according to theinformation about the to-be-accessed DCN.

With reference to the fourth aspect, in a first possible implementationof the fourth aspect, the first DCN information includes a type of theat least one DCN;

the selection module is specifically configured to select, from the atleast one DCN, a DCN whose type matches a service type of the userequipment UE, as the to-be-accessed DCN; and

the sending module is specifically configured to send the type of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the typeof the to-be-accessed DCN.

With reference to the fourth aspect, in a second possible implementationof the fourth aspect, the first DCN information includes a type, a DCNidentity ID, and a priority of the at least one DCN;

the selection module is specifically configured to: select, from the atleast one DCN, one or more DCNs whose types match a service type of theUE; and when a type of one DCN matches the service type, determine theone DCN as the to-be-accessed DCN; or when types of multiple DCNs matchthe service type, select the to-be-accessed DCN from the multiple DCNsaccording to the priority; and

the sending module is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

With reference to any one of the fourth aspect, or the first or thesecond possible implementation of the fourth aspect, in a third possibleimplementation of the fourth aspect, the sending module is furtherconfigured to send a first message to the access network device, wherethe first message is used to indicate a DCN selection capability of theUE; and

the receiving module is specifically configured to receive a secondmessage that is sent by the access network device according to the firstmessage, where the second message includes the first DCN information.

With reference to the fourth aspect, in a fourth possible implementationof the fourth aspect, the first DCN information includes a type of theat least one DCN;

the selection module is specifically configured to determine ato-be-accessed public land mobile network PLMN according to a firstpreset rule, and select, from at least one DCN supported by theto-be-accessed PLMN, a DCN whose type matches a service type of the UE,as the to-be-accessed DCN; and

the sending module is specifically configured to send the type of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the typeof the to-be-accessed DCN.

With reference to the fourth aspect, in a fifth possible implementationof the fourth aspect, the first DCN information includes a type of theat least one DCN;

the selection module is specifically configured to select, from the atleast one DCN, a DCN whose type matches a service type of the UE, as theto-be-accessed DCN, and determine a to-be-accessed PLMN according to thetype of the to-be-accessed DCN; and the sending module is specificallyconfigured to send the type of the to-be-accessed DCN to the accessnetwork device, so that the access network device determines the corenetwork device according to the type of the to-be-accessed DCN.

With reference to the fourth aspect, in a sixth possible implementationof the fourth aspect, the first DCN information includes a type, a DCNID, and a priority of the at least one DCN;

the selection module is specifically configured to: determine ato-be-accessed PLMN according to a first preset rule; select, from atleast one DCN supported by the to-be-accessed PLMN, one or more DCNswhose types match a service type of the UE; and when a type of one DCNmatches the service type, determine the one DCN as the to-be-accessedDCN; or when types of multiple DCNs match the service type, select theto-be-accessed DCN from the multiple DCNs according to the priority; and

the sending module is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

With reference to the fourth aspect, in a seventh possibleimplementation of the fourth aspect, the first DCN information includesa type, a DCN ID, and a priority of the at least one DCN;

the selection module is specifically configured to select, from the atleast one DCN, a DCN whose type matches a service type of the UE,determine a to-be-accessed PLMN according to the type of the DCN whosetype matches the service type of the UE, and select, according to thepriority and from at least one DCN supported by the to-be-accessed PLMN,a DCN with the highest priority as the to-be-accessed DCN; and

the sending module is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

With reference to any one of the fourth aspect, or the fourth to theseventh possible implementations of the fourth aspect, in an eighthpossible implementation of the fourth aspect, the receiving module isspecifically configured to receive a third message sent by the accessnetwork device, where the third message includes the first DCNinformation.

With reference to any one of the fourth to the eighth possibleimplementations of the fourth aspect, in a ninth possible implementationof the fourth aspect, the sending module is further configured torequest, to the access network device, to establish a wirelessconnection.

With reference to any one of the fourth aspect, or the first to theninth possible implementations of the fourth aspect, in a tenth possibleimplementation of the fourth aspect, the selection module is furtherconfigured to: select a preset default DCN as the to-be-accessed DCNwhen the at least one DCN includes no DCN whose type matches the servicetype; or send an access termination request to the access network devicewhen the at least one DCN includes no DCN whose type matches the servicetype; or obtain the first DCN information from another access networkdevice when the at least one DCN includes no DCN whose type matches theservice type.

According to a fifth aspect, an embodiment of the present inventionprovides an access network device, including:

a sending module, configured to send first dedicated core network DCNinformation to user equipment UE, so that the UE selects ato-be-accessed DCN according to the first DCN information, where thefirst DCN information includes information about at least one DCN thatcan be accessed by the access network device;

a receiving module, configured to receive information about theto-be-accessed DCN sent by the UE; and

a determining module, configured to determine a core network deviceaccording to the information about the to-be-accessed DCN andpreconfigured second DCN information, and initiate a service request tothe core network device.

With reference to the fifth aspect, in a first possible implementationof the fifth aspect, the information about the to-be-accessed DCNincludes a type of the to-be-accessed DCN; and

the determining module is specifically configured to determine,according to the type of the to-be-accessed DCN and the second DCNinformation, a DCN function entity group identifier corresponding to thetype of the to-be-accessed DCN, and determine the core network deviceaccording to the DCN function entity group identifier and a secondpreset rule.

With reference to the fifth aspect, in a second possible implementationof the fifth aspect, the determining module is further configured to:determine a preset default core network device as the core networkdevice when no DCN function entity group identifier corresponding to thetype of the to-be-accessed DCN is determined according to the type ofthe to-be-accessed DCN and the second DCN information; or send a fourthmessage to the UE when no DCN function entity group identifiercorresponding to the type of the to-be-accessed DCN is determinedaccording to the type of the to-be-accessed DCN and the second DCNinformation, where the fourth message is used to terminate an accessrequest.

With reference to the fifth aspect, in a third possible implementationof the fifth aspect, the information about the to-be-accessed DCNincludes a DCN ID of the to-be-accessed DCN; and

the determining module is specifically configured to determine,according to the DCN ID of the to-be-accessed DCN and the second DCNinformation, a DCN function entity group identifier corresponding to theto-be-accessed DCN, and determine the core network device according tothe DCN function entity group identifier and a second preset rule.

With reference to the third possible implementation of the fifth aspect,in a fourth possible implementation of the fifth aspect, the determiningmodule is further configured to: determine a preset default core networkdevice as the core network device when no DCN function entity groupidentifier corresponding to the DCN ID of the to-be-accessed DCN isdetermined according to the DCN ID of the to-be-accessed DCN and thesecond DCN information; or send a fourth message to the UE when no DCNfunction entity group identifier corresponding to the DCN ID of theto-be-accessed DCN is determined according to the DCN ID of theto-be-accessed DCN and the second DCN information, where the fourthmessage is used to terminate an access request.

With reference to any one of the fifth aspect, or the first to thefourth possible implementations of the fifth aspect, in a fifth possibleimplementation of the fifth aspect, the receiving module is furtherconfigured to obtain the second DCN information from the core networkdevice, where the second DCN information includes a type and a DCNfunction entity group identifier of the at least one DCN.

With reference to the fifth possible implementation of the fifth aspect,in a sixth possible implementation of the fifth aspect, the second DCNinformation further includes a DCN ID and a priority of the at least oneDCN.

With reference to any one of the fifth aspect, the first or the secondpossible implementation of the fifth aspect, or the fifth or the sixthpossible implementation of the fifth aspect, in a seventh possibleimplementation of the fifth aspect, the receiving module is furtherconfigured to receive a first message sent by the UE, where the firstmessage is used to indicate a DCN selection capability of the UE; and

the sending module is specifically configured to send a second messageto the UE according to the first message, where the second messageincludes the first DCN information.

With reference to any one of the fifth aspect, or the third to the sixthpossible implementations of the fifth aspect, in an eighth possibleimplementation of the fifth aspect, the sending module is specificallyconfigured to send a third message to the UE, where the third messageincludes the first DCN information.

According to a sixth aspect, an embodiment of the present inventionprovides a core network device, including:

a sending module, configured to send second dedicated core network DCNinformation to an access network device, so that the access networkdevice determines the core network device according to the second DCNinformation; and

a processing module, configured to process a service request initiatedby the access network device.

With reference to the sixth aspect, in a first possible implementationof the sixth aspect, the second DCN information includes a type and aDCN function entity group identifier of at least one DCN.

With reference to the first possible implementation of the sixth aspect,in a second possible implementation of the sixth aspect, the second DCNinformation further includes a DCN ID and a priority of the at least oneDCN.

According to a seventh aspect, an embodiment of the present inventionprovides user equipment UE, including:

a receiver, configured to obtain first dedicated core network DCNinformation from an access network device, where the first DCNinformation includes information about at least one DCN that can beaccessed by the access network device;

a processor, configured to select a to-be-accessed DCN from the at leastone DCN according to the first DCN information; and

a transmitter, configured to send information about the to-be-accessedDCN to the access network device, so that the access network devicedetermines a core network device according to the information about theto-be-accessed DCN.

With reference to the seventh aspect, in a first possible implementationof the seventh aspect, the first DCN information includes a type of theat least one DCN;

the processor is specifically configured to select, from the at leastone DCN, a DCN whose type matches a service type of the user equipmentUE, as the to-be-accessed DCN; and

the transmitter is specifically configured to send the type of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the typeof the to-be-accessed DCN.

With reference to the seventh aspect, in a second possibleimplementation of the seventh aspect, the first DCN information includesa type, a DCN identity ID, and a priority of the at least one DCN;

the processor is specifically configured to: select, from the at leastone DCN, one or more DCNs whose types match a service type of the UE;and when a type of one DCN matches the service type, determine the oneDCN as the to-be-accessed DCN; or when types of multiple DCNs match theservice type, select the to-be-accessed DCN from the multiple DCNsaccording to the priority; and

the transmitter is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

With reference to any one of the seventh aspect, or the first or thesecond possible implementation of the seventh aspect, in a thirdpossible implementation of the seventh aspect, the transmitter isfurther configured to send a first message to the access network device,where the first message is used to indicate a DCN selection capabilityof the UE; and

the receiver is specifically configured to receive a second message thatis sent by the access network device according to the first message,where the second message includes the first DCN information.

With reference to the seventh aspect, in a fourth possibleimplementation of the seventh aspect, the first DCN information includesa type of the at least one DCN;

the processor is specifically configured to determine a to-be-accessedpublic land mobile network PLMN according to a first preset rule, andselect, from at least one DCN supported by the to-be-accessed PLMN, aDCN whose type matches a service type of the UE, as the to-be-accessedDCN; and

the transmitter is specifically configured to send the type of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the typeof the to-be-accessed DCN.

With reference to the seventh aspect, in a fifth possible implementationof the seventh aspect, the first DCN information includes a type of theat least one DCN;

the processor is specifically configured to select, from the at leastone DCN, a DCN whose type matches a service type of the UE, as theto-be-accessed DCN, and determine a to-be-accessed PLMN according to thetype of the to-be-accessed DCN; and

the transmitter is specifically configured to send the type of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the typeof the to-be-accessed DCN.

With reference to the seventh aspect, in a sixth possible implementationof the seventh aspect, the first DCN information includes a type, a DCNID, and a priority of the at least one DCN;

the processor is specifically configured to: determine a to-be-accessedPLMN according to a first preset rule; select, from at least one DCNsupported by the to-be-accessed PLMN, one or more DCNs whose types matcha service type of the UE; and when a type of one DCN matches the servicetype, determine the one DCN as the to-be-accessed DCN; or when types ofmultiple DCNs match the service type, select the to-be-accessed DCN fromthe multiple DCNs according to the priority; and

the transmitter is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

With reference to the seventh aspect, in a seventh possibleimplementation of the seventh aspect, the first DCN information includesa type, a DCN ID, and a priority of the at least one DCN;

the processor is specifically configured to select, from the at leastone DCN, a DCN whose type matches a service type of the UE, determine ato-be-accessed PLMN according to the type of the DCN whose type matchesthe service type of the UE, and select, according to the priority andfrom at least one DCN supported by the to-be-accessed PLMN, a DCN withthe highest priority as the to-be-accessed DCN; and

the transmitter is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

With reference to any one of the seventh aspect, or the fourth to theseventh possible implementations of the seventh aspect, in an eighthpossible implementation of the seventh aspect, the receiver isspecifically configured to receive a third message sent by the accessnetwork device, where the third message includes the first DCNinformation.

With reference to any one of the fourth to the eighth possibleimplementations of the seventh aspect, in a ninth possibleimplementation of the seventh aspect, the transmitter is furtherconfigured to request, to the access network device, to establish awireless connection.

With reference to any one of the seventh aspect, or the first to theninth possible implementations of the seventh aspect, in a tenthpossible implementation of the seventh aspect, the processor is furtherconfigured to: select a preset default DCN as the to-be-accessed DCNwhen the at least one DCN includes no DCN whose type matches the servicetype; or send an access termination request to the access network devicewhen the at least one DCN includes no DCN whose type matches the servicetype; or obtain the first DCN information from another access networkdevice when the at least one DCN includes no DCN whose type matches theservice type.

According to an eighth aspect, an embodiment of the present inventionprovides an access network device, including:

a transmitter, configured to send first dedicated core network DCNinformation to user equipment UE, so that the UE selects ato-be-accessed DCN according to the first DCN information, where thefirst DCN information includes information about at least one DCN thatcan be accessed by the access network device;

a receiver, configured to receive information about the to-be-accessedDCN sent by the UE; and

a processor, configured to determine a core network device according tothe information about the to-be-accessed DCN and preconfigured secondDCN information, and initiate a service request to the core networkdevice.

With reference to the eighth aspect, in a first possible implementationof the eighth aspect, the information about the to-be-accessed DCNincludes a type of the to-be-accessed DCN;

the processor is specifically configured to determine, according to thetype of the to-be-accessed DCN and the second DCN information, a DCNfunction entity group identifier corresponding to the type of theto-be-accessed DCN, and determine the core network device according tothe DCN function entity group identifier and a second preset rule.

With reference to the first possible implementation of the eighthaspect, in a second possible implementation of the eighth aspect, theprocessor is further configured to: determine a preset default corenetwork device as the core network device when no DCN function entitygroup identifier corresponding to the type of the to-be-accessed DCN isdetermined according to the type of the to-be-accessed DCN and thesecond DCN information; or send a fourth message to the UE when no DCNfunction entity group identifier corresponding to the type of theto-be-accessed DCN is determined according to the type of theto-be-accessed DCN and the second DCN information, where the fourthmessage is used to terminate an access request.

With reference to the eighth aspect, in a third possible implementationof the eighth aspect, the information about the to-be-accessed DCNincludes a DCN ID of the to-be-accessed DCN; and

the processor is specifically configured to determine, according to theDCN ID of the to-be-accessed DCN and the second DCN information, a DCNfunction entity group identifier corresponding to the to-be-accessedDCN, and determine the core network device according to the DCN functionentity group identifier and a second preset rule.

With reference to the third possible implementation of the eighthaspect, in a fourth possible implementation of the eighth aspect, theprocessor is further configured to: determine a preset default corenetwork device as the core network device when no DCN function entitygroup identifier corresponding to the DCN ID of the to-be-accessed DCNis determined according to the DCN ID of the to-be-accessed DCN and thesecond DCN information; or send a fourth message to the UE when no DCNfunction entity group identifier corresponding to the DCN ID of theto-be-accessed DCN is determined according to the DCN ID of theto-be-accessed DCN and the second DCN information, where the fourthmessage is used to terminate an access request.

With reference to any one of the eighth aspect, or the first to thefourth possible implementations of the eighth aspect, in a fifthpossible implementation of the eighth aspect, the receiver is furtherconfigured to obtain the second DCN information from the core networkdevice, where the second DCN information includes a type and a DCNfunction entity group identifier of the at least one DCN.

With reference to the fifth possible implementation of the eighthaspect, in a sixth possible implementation of the eighth aspect, thesecond DCN information further includes a DCN ID and a priority of theat least one DCN.

With reference to any one of the eighth aspect, the first or the secondpossible implementation of the eighth aspect, or the fifth or the sixthpossible implementation of the eighth aspect, in a seventh possibleimplementation of the eighth aspect, the receiver is further configuredto receive a first message sent by the UE, where the first message isused to indicate a DCN selection capability of the UE; and

the transmitter is specifically configured to send a second message tothe UE according to the first message, where the second message includesthe first DCN information.

With reference to any one of the eighth aspect, or the third to thesixth possible implementations of the eighth aspect, in an eighthpossible implementation of the eighth aspect, the transmitter isspecifically configured to send a third message to the UE, where thethird message includes the first DCN information.

According to a ninth aspect, an embodiment of the present inventionprovides a core network device, including:

a transmitter, configured to send second dedicated core network DCNinformation to an access network device, so that the access networkdevice determines the core network device according to the second DCNinformation; and

a processor, configured to process a service request initiated by theaccess network device.

With reference to the ninth aspect, in a first possible implementationof the ninth aspect, the second DCN information includes a type and aDCN function entity group identifier of at least one DCN.

With reference to the first possible implementation of the ninth aspect,in a second possible implementation of the ninth aspect, the second DCNinformation further includes a DCN ID and a priority of the at least oneDCN.

According to a tenth aspect, an embodiment of the present inventionprovides a communications system, including user equipment UE, an accessnetwork device, and a core network device, where the UE is the UEaccording to any one of the fourth aspect, or the first to the tenthpossible implementations of the fourth aspect, the access network deviceis the device according to any one of the fifth aspect, or the first tothe eighth possible implementations of the fifth aspect, and the corenetwork device is the device according to any one of the sixth aspect,or the first or the second possible implementation of the sixth aspect.

According to an eleventh aspect, an embodiment of the present inventionprovides a communications system, including user equipment UE, an accessnetwork device, and a core network device, where the UE is the UEaccording to any one of the seventh aspect, or the first to the tenthpossible implementations of the seventh aspect, the access networkdevice is the device according to any one of the eighth aspect, or thefirst to the eighth possible implementations of the eighth aspect, andthe core network device is the device according to any one of the ninthaspect, or the first or the second possible implementation of the ninthaspect.

According to the core network selection method, the apparatus, and thesystem provided in the embodiments of the present invention, UE selectsa to-be-accessed DCN according to a service type of the UE, so as toimplement accurate selection of a core network device by an accessnetwork device, improve accuracy of DCN selection by the access networkdevice, avoid a communication signaling increase and a processing delayin a DCN reselection process, and improve communication efficiency.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly describes the accompanyingdrawings required for describing the embodiments or the prior art.Apparently, the accompanying drawings in the following description showsome embodiments of the present invention, and persons of ordinary skillin the art may still derive other drawings from these accompanyingdrawings without creative efforts.

FIG. 1 is a flowchart of an embodiment of a core network selectionmethod according to the present invention;

FIG. 2 is a flowchart of another embodiment of a core network selectionmethod according to the present invention;

FIG. 3 is a flowchart of still another embodiment of a core networkselection method according to the present invention;

FIG. 4 is a flowchart of yet another embodiment of a core networkselection method according to the present invention;

FIG. 5A and FIG. 5B are a flowchart of a fifth embodiment of a corenetwork selection method according to the present invention;

FIG. 6A and FIG. 6B are a flowchart of a sixth embodiment of a corenetwork selection method according to the present invention;

FIG. 7A and FIG. 7B are a flowchart of a seventh embodiment of a corenetwork selection method according to the present invention;

FIG. 8 is a flowchart of an eighth embodiment of a core networkselection method according to the present invention;

FIG. 9 is a flowchart of a ninth embodiment of a core network selectionmethod according to the present invention;

FIG. 10 is a flowchart of a tenth embodiment of a core network selectionmethod according to the present invention;

FIG. 11 is a schematic structural diagram of an embodiment of UEaccording to the present invention;

FIG. 12 is a schematic structural diagram of an embodiment of an accessnetwork device according to the present invention;

FIG. 13 is a schematic structural diagram of an embodiment of a corenetwork device according to the present invention;

FIG. 14 is a schematic structural diagram of another embodiment of UEaccording to the present invention;

FIG. 15 is a schematic structural diagram of another embodiment of anaccess network device according to the present invention;

FIG. 16 is a schematic structural diagram of another embodiment of acore network device according to the present invention; and

FIG. 17 is a schematic structural diagram of an embodiment of acommunications system according to the present invention.

DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of theembodiments of the present invention clearer, the following clearlydescribes the technical solutions in the embodiments of the presentinvention with reference to the accompanying drawings in the embodimentsof the present invention. Apparently, the described embodiments are somebut not all of the embodiments of the present invention. All otherembodiments obtained by persons of ordinary skill in the art based onthe embodiments of the present invention without creative efforts shallfall within the protection scope of the present invention.

FIG. 1 is a flowchart of an embodiment of a core network selectionmethod according to the present invention. As shown in FIG. 1, themethod in this embodiment may include the following steps.

Step 101: Obtain first DCN information from an access network device,where the first DCN information includes information about at least oneDCN that can be accessed by the access network device.

The core network selection method is applicable to a communicationssystem in which network slicing is performed on a core network. A DCNcorresponding to a single network slice may be defined as a set offunction entities supporting a communications service requirement in aspecific scenario, for example, a mobility management entity (MobilityManagement Entity, MME for short) on a 4G network and a serving GPRSsupport node (Serving GPRS Support Node, SGSN for short) on a 3Gnetwork. This embodiment may be executed by user equipment (UserEquipment, UE for short). The UE obtains the first DCN information fromthe access network device. The access network device may be an evolvedNodeB (evolved Node B, eNB for short), a radio access network node(Radio Access Network Node, RAN Node for short), or the like. Based ondeployment of the communications system and a function of each DCN, theaccess network device may access one or more DCNs. Duringpreconfiguration of the access network device and the DCN, the accessnetwork device may obtain information about the DCN. Then, the accessnetwork device sends the information about the DCN to the UE.

Step 102: Select a to-be-accessed DCN from the at least one DCNaccording to the first DCN information.

The UE may know, according to the first DCN information obtained fromthe access network device, which DCN is a candidate DCN. Then, the UEmay select one of the candidate DCNs as the to-be-accessed DCN. A methodfor the UE to select the to-be-accessed DCN is, for example, as follows:A to-be-accessed DCN that matches a service type may be selected fromthe candidate DCNs according to the service type, including a devicetype of the UE, a use type of the UE, and the like. For example, if ause type of the UE is a common network service, a to-be-accessed DCNselected by the UE needs to be responsible mainly for a service relatedto a mobile broadband network. Alternatively, the UE may select, fromthe candidate DCNs, a DCN with the highest priority as theto-be-accessed DCN, or randomly select one of the candidate DCNs as theto-be-accessed DCN.

Step 103: Send information about the to-be-accessed DCN to the accessnetwork device, so that the access network device determines a corenetwork device according to the information about the to-be-accessedDCN.

After selecting the to-be-accessed DCN, the UE sends the informationabout the to-be-accessed DCN to the access network device. Then, theaccess network device can determine the core network device combiningwith a DCN function entity group identifier of the to-be-accessed DCN.

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 2 is a flowchart of another embodiment of a core network selectionmethod according to the present invention. As shown in FIG. 2, themethod in this embodiment may include the following steps.

Step 201: Send first DCN information to UE, so that the UE selects ato-be-accessed DCN according to the first DCN information, where thefirst DCN information includes information about at least one DCN thatcan be accessed by an access network device.

This embodiment corresponds to the method embodiment shown in FIG. 1,and is executed by the access network device. The access network devicesends, to the UE, the first DCN information that includes theinformation about the at least one DCN that can be accessed by theaccess network device, so that the UE performs step 102 and selects theto-be-accessed DCN.

Step 202: Receive information about the to-be-accessed DCN sent by theUE.

Step 203: Determine a core network device according to the informationabout the to-be-accessed DCN and preconfigured second DCN information,and initiate a service request to the core network device.

After obtaining the information about the to-be-accessed DCN, the accessnetwork device selects the final core network device according to theinformation about the to-be-accessed DCN and the preconfigured secondDCN information. The second DCN information is preconfigured by theaccess network device and the at least one DCN that can be accessed bythe access network device, and includes the information about the atleast one DCN, for example, a type, a DCN identity (identity, ID forshort), a priority, and a DCN function entity group identifier. Theaccess network device selects, from the second DCN information, a corenetwork device that matches the information about the to-be-accessedDCN, as the core network device. Then, the access network device cansend the service request of the UE to the core network device forprocessing.

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 3 is a flowchart of still another embodiment of a core networkselection method according to the present invention. As shown in FIG. 3,the method in this embodiment may include the following steps.

Step 301: Send second DCN information to an access network device, sothat the access network device determines a core network deviceaccording to the second DCN information.

This embodiment corresponds to the method embodiment shown in FIG. 2,and is executed by the core network device. Before the access networkdevice determines the core network device, the core network device needsto perform DCN information configuration interaction with the accessnetwork device. The access network device communicates with the corenetwork device in an accessible DCN, and the core network device sendsDCN information of the core network device to the access network device.Therefore, a list of information about one or more DCNs can be formed onthe access network device.

Step 302: Process a service request initiated by the access networkdevice.

After establishing a connection to the access network device, the corenetwork device can process the service request sent by the accessnetwork device.

According to this embodiment, a core network device and an accessnetwork device preconfigure DCN information, so as to implement accurateselection of the core network device by the access network device,improve accuracy of DCN selection by the access network device, avoid acommunication signaling increase and a processing delay in a DCNreselection process, and improve communication efficiency.

In the following content, several specific embodiments are used todescribe in detail the technical solutions in the method embodimentsshown in FIG. 1 to FIG. 3.

FIG. 4 is a flowchart of yet another embodiment of a core networkselection method according to the present invention. As shown in FIG. 4,the method in this embodiment is applicable to a communications systemincluding UE, a RAN node, an MME/SGSN, and a home subscriber server(Home Subscriber Server, HHS for short). The MME/SGSN is the foregoingcore network device, and the HSS is a core network device that providesa core network user plane function. It should be noted that the methodin this embodiment may be applicable to any communications system thatincludes UE, an access network device, and a core network device. Forease of method embodiment description, the foregoing communicationssystem is merely an example. The method in this embodiment may includethe following steps.

S401: The MME/SGSN sends second DCN information to the RAN node, wherethe second DCN information includes a type and a DCN function entitygroup identifier of at least one DCN that can be accessed by the RANnode.

In this embodiment, the MME/SGSN configures the second DCN informationto the RAN node. The second DCN information may include a list ofinformation about the one or more DCNs that can be accessed by the RANnode, and each list item includes the following attribute information: aDCN type (DCN Type) and a DCN function entity group identifier (forexample, an MME group identifier (Group ID), an SGSN group ID, or adefault NRI). The DCN type indicates a specific communications serviceor communication scenario supported by the DCN. For example, the DCNtype is a Cellular Internet of Things (CIoT), an ultra-reliablecommunication (Ultra-Reliable Communication, URC for short) network, amobile broadband network (MBB), or the like.

S402: The UE sends a first message to the RAN node, where the firstmessage is used to indicate a DCN selection capability of the UE.

The first message may be a radio resource control (Radio ResourceControl, RRC for short) connection request message (RRC ConnectionRequest). When sending the RRC connection request to the RAN node, theUE may add, to the RRC connection request, indication information thatindicates the DCN selection capability of the UE, so as to indicate thatthe UE is capable of selecting a DCN.

S403: The RAN node sends a second message to the UE, where the secondmessage includes first DCN information, and the first DCN informationincludes the type of the at least one DCN that can be accessed by theRAN node.

The second message may be an RRC connection setup message (RRCConnection Setup). The RAN node adds the first DCN information to theRRC connection setup that is sent as a reply. The first DCN informationincludes the type of the at least one DCN that can be accessed by theRAN node.

S404: The UE selects, from the at least one DCN that can be accessed bythe RAN node, a DCN whose type matches a service type, as ato-be-accessed DCN.

The UE selects, according to the service type including a use type ofthe UE and a device type of the UE, a DCN type that matches the servicetype. For example, if the UE is used as a common meter or a commonsensor, a DCN type that matches the service type is CIoT; if the UE isused as a transport tool or for telemedicine, a DCN type that matchesthe service type is URC; if the UE is used for a common network serviceof entertainment or of monitoring, a DCN type that matches the servicetype is MBB. The UE may determine the to-be-accessed DCN according tothe DCN type that matches the service type.

In addition, when the UE does not find any DCN whose type matches theservice type, the UE may select a preset default DCN as theto-be-accessed DCN. The default DCN may be preconfigured by the MME/SGSNfor the RAN node, and then the RAN node sends information about thedefault DCN to the UE by using an RRC connection setup. Alternatively,the UE may send an access termination request to the RAN node, toterminate this connection request process. Alternatively, the UE mayperform a process such as PLMN reselection and/or cell reselection, andobtain the first DCN information from another RAN node.

S405: The UE sends the type of the to-be-accessed DCN to the RAN node.

The UE may encapsulate the type of the to-be-accessed DCN into an RRCconnection setup complete message (RRC Connection Setup Complete), tosend the type of the to-be-accessed DCN to the RAN node. In addition,the RRC connection setup complete may further carry a non-access stratum(Non-Access Stratum, NAS for short) message, for example, an attach(Attach) request message, a tracking area update (Tracking Area Update,TAU for short) request message, a route area update (Route Area Update,RAU for short) request message, or a service request (Service Request)message.

S406: The RAN node determines, according to the type of theto-be-accessed DCN and the second DCN information, a DCN function entitygroup identifier corresponding to the type of the to-be-accessed DCN.

The RAN node can determine, according to the DCN type and the second DCNinformation, the DCN function entity group identifier corresponding tothe DCN type. If the second DCN information includes no DCN functionentity group identifier corresponding to the DCN type, the RAN node mayselect a default DCN or send an RRC connection reject message (RRCConnection Reject) to the UE, where the RRC connection reject carries areject cause “no DCN available (No DCN available)”, and the RAN nodedoes not perform any subsequent step.

S407: The RAN node determines the MME/SGSN according to the DCN functionentity group identifier and a second preset rule.

The RAN node further selects one function entity, such as an MME in 4Gor an SGSN in 3G, in the DCN corresponding to the DCN function entitygroup identifier, as the core network device. The second preset rule mayinclude, for example, selecting, according to a load status of eachfunction entity in a DCN function entity group corresponding to the DCNfunction entity group identifier and according to a load balancing (LoadBalancing) principle, a function entity with relatively low load as thecore network device used for processing a UE service request.

S408: The RAN node initiates a service request to the MME/SGSN.

S409: The UE, the RAN node, the MME/SGSN, and the HSS together completeservice processing.

The RAN node forwards the NAS message in the RRC connection setupcomplete message to the determined MME/SGSN. The MME/SGSN processes theNAS message, and sends a create session message to the HSS in theto-be-accessed DCN. The MME/SGSN, the HSS, the RAN node, and the UEtogether complete a NAS process corresponding to the NAS message.

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 5A and FIG. 5B are a flowchart of a fifth embodiment of a corenetwork selection method according to the present invention. As shown inFIG. 5A and FIG. 5B, the method in this embodiment is applicable to acommunications system including UE, a RAN node, an MME/SGSN, and an HHS.The MME/SGSN is the foregoing core network device, and the HSS is a corenetwork device that provides a core network user plane function. Itshould be noted that the method in this embodiment may be applicable toany communications system that includes UE, an access network device,and a core network device. For ease of method embodiment description,the foregoing communications system is merely an example. The method inthis embodiment may include the following steps.

S501: The MME/SGSN sends second DCN information to the RAN node, wherethe second DCN information includes a type, a DCN ID, a priority, and aDCN function entity group identifier of at least one DCN that can beaccessed by the RAN node.

In this embodiment, the MME/SGSN configures the second DCN informationto the RAN node. The second DCN information may include a list ofinformation about the one or more DCNs that can be accessed by the RANnode, and each list item includes the following attribute information: aDCN type (DCN Type) and a DCN function entity group identifier (forexample, an MME group identifier (Group ID), an SGSN group ID, or adefault NRI). The DCN type indicates a specific communications serviceor communication scenario supported by the DCN. For example, the DCNtype is a Cellular Internet of Things (CIoT), an ultra-reliablecommunication (Ultra-Reliable Communication, URC for short) network, amobile broadband network (MBB), or the like. A DCN ID may be defined asa unique identity, for example, 1 or 2, of a DCN within one public landmobile network (Public Land Mobile Network, PLMN for short).Alternatively, a DCN ID may be defined as a globally unique ID of a DCN.For example, DCN ID=PLMN ID+DCN local ID=MCC+MNC+DCN local ID, where DCNlocal ID is a unique identity of a DCN within one PLMN. For example, ifMCC=460, MNC=10, and DCN local ID=1, then DCN ID=460101. DCN type-DCN IDmapping may be one-to-one mapping or one-to-many mapping. When one DCNtype corresponds to multiple DCN IDs, each DCN ID may further correspondto one priority level. Table 1 is a schematic table of the second DCNinformation.

TABLE 1 DCN ID DCN type Priority DCN function entity group identifier 1CIoT 1 MMEGI: 1100 . . . 00 2 CIoT 2 MMEGI: 1100 . . . 01 3 MBB 1 MMEGI:1011 . . . 01

S502: The UE sends a first message to the RAN node, where the firstmessage is used to indicate a DCN selection capability of the UE.

A principle of S502 is similar to that of S402, and details are notdescribed herein again.

S503: The RAN node sends a second message to the UE, where the secondmessage includes first DCN information, and the first DCN informationincludes the type, DCN ID, and priority of the at least one DCN that canbe accessed by the RAN node.

A principle of S503 is similar to that of S403. The only difference liesin that, in this embodiment, the first DCN information further includesthe DCN ID and priority of the at least one DCN that can be accessed bythe RAN node. Details are not described herein again.

S504: The UE selects, from the at least one DCN, one or more DCNs whosetypes match a service type.

The UE selects, according to the service type including a use type ofthe UE and a device type of the UE, a DCN type that matches the servicetype. For example, if the UE is used as a common meter or a commonsensor, a DCN type that matches the service type is CIoT; if the UE isused as a transport tool or for telemedicine, a DCN type that matchesthe service type is URC; if the UE is used for a common network serviceof entertainment or of monitoring, a DCN type that matches the servicetype is MBB. The UE may determine one or more DCNs according to the DCNtype that matches the service type. When one DCN is determined, itindicates that DCN type-DCN ID mapping is one-to-one mapping. Whenmultiple DCNs are determined, it indicates that DCN type-DCN ID mappingis one-to-many mapping.

S505 a: When a type of one DCN matches the service type, the UEdetermines the one DCN as a to-be-accessed DCN.

If there is only one DCN whose type matches the service type, the UEdirectly obtains a DCN ID of the DCN.

S505 b: When types of multiple DCNs match the service type, the UEselects a to-be-accessed DCN from the multiple DCNs according to thepriority.

When there are multiple DCNs whose types match the service type, apriority may be set for a DCN ID of each DCN. After determining the DCNtypes, the UE may further select a DCN ID according to a priority. Forexample, DCN type=CIoT, and correspondingly, DCN ID=460101 or 460102. ADCN whose DCN ID=460101 is a commercial network, and has a priority of 1(high-priority). A DCN whose DCN ID=460102 is an experimental network,and has a priority of 2 (low-priority). The UE may continue to select,according to the service type, a DCN with a matching priority level asthe to-be-accessed DCN. A priority of a DCN may be changed. For example,when the DCN whose DCN ID=460102 is tested and is upgraded to acommercial network, and has better performance than the DCN whose DCNID=460101 does, the priority for DCN ID=460102 may be changed to 1, andthe priority for DCN ID=460101 may be changed to 2.

S505 a and S505 b are alternative steps. The step to be performed isdetermined according to a quantity of DCNs whose types match the servicetype.

In addition, when the UE does not find any DCN whose type matches theservice type, the UE may select a preset default DCN as theto-be-accessed DCN. The default DCN may be preconfigured by the MME/SGSNfor the RAN node, and then the RAN node sends information about thedefault DCN to the UE by using an RRC connection setup. Alternatively,the UE may send an access termination request to the RAN node, toterminate this connection request process. Alternatively, the UE mayperform a process such as PLMN reselection and/or cell reselection, andobtain the first DCN information from another RAN node.

S506: The UE sends the DCN ID of the to-be-accessed DCN to the RAN node.

A principle of S506 is similar to that of S405. The only difference liesin that, in this embodiment, the UE encapsulates the DCN ID of theto-be-accessed DCN into the RRC connection setup complete, to send theDCN ID of the to-be-accessed DCN to the RAN node. Details are notdescribed herein again.

S507: The RAN node determines, according to the DCN ID of theto-be-accessed DCN and the second DCN information, a DCN function entitygroup identifier corresponding to the DCN ID of the to-be-accessed DCN.

A principle of S507 is similar to that of S406. The only difference liesin that, in this embodiment, the RAN node determines the DCN functionentity group identifier according to the DCN ID of the to-be-accessedDCN. Details are not described herein again.

S508: The RAN node determines the MME/SGSN according to the DCN functionentity group identifier and a second preset rule.

A principle of S508 is similar to that of S407, and details are notdescribed herein again.

S509: The RAN node initiates a service request to the MME/SGSN.

S510: The UE, the RAN node, the MME/SGSN, and the HSS together completeservice processing.

Principles of S509 and S510 are similar to those of S408 and S409, anddetails are not described herein again.

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 6A and FIG. 6B are a flowchart of a sixth embodiment of a corenetwork selection method according to the present invention. As shown inFIG. 6A and FIG. 6B, the method in this embodiment is applicable to acommunications system including UE, a RAN node, an MME/SGSN, and an HHS.The MME/SGSN is the foregoing core network device, and the HSS is a corenetwork device that provides a core network user plane function. Itshould be noted that the method in this embodiment may be applicable toany communications system that includes UE, an access network device,and a core network device. For ease of method embodiment description,the foregoing communications system is merely an example. The method inthis embodiment may include the following steps.

S601: The MME/SGSN sends second DCN information to the RAN node, wherethe second DCN information includes a type and a DCN function entitygroup identifier of at least one DCN that can be accessed by the RANnode.

A principle of S601 is similar to that of S401, and details are notdescribed herein again.

S602: The RAN node sends a third message to the UE, where the thirdmessage includes first DCN information, and the first DCN informationincludes the type of the at least one DCN that can be accessed by theRAN node.

The third message may be a broadcast message that is sent by the RANnode and that includes the type of the at least one DCN that can beaccessed by the RAN node.

The UE may select, according to the broadcast message, a PLMN and ato-be-accessed DCN in either of the two following manners:

S603 a: The UE determines the to-be-accessed PLMN according to a firstpreset rule.

The first preset rule may include, for example, the following: The UEpreferentially selects a registered PLMN (Registered PLMN) or a PLMNthat is equivalent to a registered PLMN, less preferentially selects aPLMN at a home location of the UE or a PLMN that is equivalent to a PLMNat a home location of the UE, and least preferentially selects apreferred PLMN configured by a user or an operator.

S604 a: The UE selects, from at least one DCN supported by theto-be-accessed PLMN, a DCN whose type matches a service type, as theto-be-accessed DCN.

The UE first performs a PLMN selection process, to select one PLMN IDfrom multiple PLMN IDs. Then, the UE selects, from the at least one DCNsupported by the PLMN, the DCN whose DCN type matches the service type,as the to-be-accessed DCN. A principle of a process in which the UEselects the to-be-accessed DCN is similar to that of S404, and detailsare not described herein again. In this case, the DCN type may beindicated as a parameter included in information about each PLMN in thebroadcast message. That is, the information about each PLMN may include{PLMN ID, {DCN type1, DCN type2}, . . . }.

S603 b: The UE selects, from the at least one DCN that can be accessedby the RAN node, a DCN whose type matches a service type, as theto-be-accessed DCN.

S604 b: The UE determines the to-be-accessed PLMN according to the typeof the to-be-accessed DCN.

The UE first selects, from the at least one DCN that can be accessed bythe RAN node, the DCN whose DCN type matches the service type. Aprinciple of a process in which the UE selects the DCN whose typematches the service type is similar to that of S404, and details are notdescribed herein again. Then, the UE selects one PLMN from PLMNs thatsupport the DCN type of the selected DCN, as the to-be-accessed PLMN. Inthis case, information about each DCN in the broadcast message mayinclude {DCN type, {PLMN ID1, PLMN ID2}, . . . }. For example, the UEfirst selects, according to a use type (for example, the UE is used as acommon meter), a DCN whose DCN Type=CIoT, and then selects a PLMN ID2from a PLMN ID1 and the PLMN ID2 that support DCN Type=CIoT.

S603 a and S604 a, and S603 b and S604 b are alternative steps. The UEcan select the PLMN and the to-be-accessed DCN by using either of thetwo methods.

In addition, when the UE does not find any DCN whose type matches theservice type, the UE may select a preset default DCN as theto-be-accessed DCN. The default DCN may be preconfigured by the MME/SGSNfor the RAN node, and then the RAN node sends information about thedefault DCN to the UE by using an RRC connection setup. Alternatively,the UE may send an access termination request to the RAN node, toterminate this connection request process. Alternatively, the UE mayperform a process such as PLMN reselection and/or cell reselection, andobtain the first DCN information from another RAN node.

S605: The UE requests, to the RAN node, to establish a wirelessconnection.

That the UE requests, to the RAN node, to establish a wirelessconnection is performing a cell selection process. The UE selects a cellof the PLMN selected in the foregoing step, and performs a random accessprocess to establish a connection to the RAN node. The UE may send anRRC connection request to the RAN node. The RAN node replies with an RRCconnection setup.

S606: The UE sends the type of the to-be-accessed DCN to the RAN node.

A principle of S606 is similar to that of S405, and details are notdescribed herein again.

S607: The RAN node determines, according to the type of theto-be-accessed DCN and the second DCN information, a DCN function entitygroup identifier corresponding to the type of the to-be-accessed DCN.

A principle of S607 is similar to that of S406, and details are notdescribed herein again.

S608: The RAN node determines the MME/SGSN according to the DCN functionentity group identifier and a second preset rule.

A principle of S608 is similar to that of S407, and details are notdescribed herein again.

S609: The RAN node initiates a service request to the MME/SGSN.

S610: The UE, the RAN node, the MME/SGSN, and the HSS together completeservice processing.

Principles of S609 and S610 are similar to those of S408 and S409, anddetails are not described herein again.

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 7A and FIG. 7B are a flowchart of a seventh embodiment of a corenetwork selection method according to the present invention. As shown inFIG. 7A and FIG. 7B, the method in this embodiment is applicable to acommunications system including UE, a RAN node, an MME/SGSN, and an HHS.The MME/SGSN is the foregoing core network device, and the HSS is a corenetwork device that provides a core network user plane function. Itshould be noted that the method in this embodiment may be applicable toany communications system that includes UE, an access network device,and a core network device. For ease of method embodiment description,the foregoing communications system is merely an example. The method inthis embodiment may include the following steps.

S701: The MME/SGSN sends second DCN information to the RAN node, wherethe second DCN information includes a type, a DCN ID, a priority, and aDCN function entity group identifier of at least one DCN that can beaccessed by the RAN node.

A principle of S701 is similar to that of S501, and details are notdescribed herein again.

S702: The RAN node sends a third message to the UE, where the thirdmessage includes first DCN information, and the first DCN informationincludes the type, DCN ID, and priority of the at least one DCN that canbe accessed by the RAN node.

A principle of S702 is similar to that of S602. The only difference liesin that, in this embodiment, the first DCN information further includesthe DCN ID and priority of the at least one DCN that can be accessed bythe RAN node. Details are not described herein again.

The UE may select, according to the broadcast message, a PLMN and ato-be-accessed DCN in either of the two following manners:

S703 a: The UE determines the to-be-accessed PLMN according to a firstpreset rule.

S704 a: The UE selects, from at least one DCN supported by theto-be-accessed PLMN, one or more DCNs whose types match a service type.

S704 a is similar to S604 a, and details are not described herein again.

S705 a: When a type of one DCN matches the service type, the UEdetermines the one DCN as the to-be-accessed DCN.

S705 b: When types of multiple DCNs match the service type, the UEselects the to-be-accessed DCN from the multiple DCNs according to thepriority.

The UE first performs a PLMN selection process, to select one PLMN IDfrom multiple PLMN IDs. Then, the UE selects the DCN type and a DCN IDfrom those of the at least one DCN supported by the PLMN. A principle ofa process in which the UE selects the DCN type and the DCN ID is similarto that of S504 to S505 b, and details are not described herein again.In this case, the DCN ID may be indicated as a parameter included ininformation about each PLMN in the broadcast message. That is, theinformation about each PLMN may include {PLMN ID, {DCN type1, DCN ID1,DCN ID2}, {DCN type2, DCN ID3, DCN ID4}, . . . }.

S703 c: The UE selects, from the at least one DCN that can be accessedby the RAN node, a DCN whose type matches a service type.

S704 c: The UE determines the to-be-accessed PLMN according to the typeof the DCN whose type matches the service type.

S705 c: The UE selects, according to the priority and from at least oneDCN supported by the to-be-accessed PLMN, a DCN with the highestpriority as the to-be-accessed DCN.

The UE first selects, from the at least one DCN that can be accessed bythe RAN node, the DCN whose DCN type matches the service type. Aprinciple of a process in which the UE selects the DCN whose typematches the service type is similar to that of S404, and details are notdescribed herein again. Then, the UE selects one PLMN from PLMNs thatsupport the DCN type of the selected DCN, as the to-be-accessed PLMN.The UE further selects, according to the priority and from the at leastone DCN supported by the to-be-accessed PLMN, the DCN with the highestpriority as the to-be-accessed DCN. DCN IDs corresponding to one PLMN IDmay be sequenced according to priorities. The UE preferentially selectsa DCN ID with a high priority. In this case, information about each DCNin the broadcast message may include {DCN type, {PLMN ID1, DCN ID1, DCNID2}, {PLMN ID2, DCN ID3, DCN ID4}, . . . }. In this case, informationabout each DCN in the broadcast message may include {DCN type, {PLMNID1, PLMN ID2}, . . . }. For example, if the UE is used as a commonmeter, the UE selects a DCN whose DCN type=CIoT, then selects a PLMN ID2from a PLMN ID1 and the PLMN ID2 that support DCN type=CIoT, and thenselects a DCN ID3 from a DCN ID of a DCN supported by the PLMN ID2.

S703 a to S705 b, and S703 c to S705 c are alternative steps. The UE canselect the PLMN and the to-be-accessed DCN by using either of the twomethods.

In addition, when the UE does not find any DCN whose type matches theservice type, the UE may select a preset default DCN as theto-be-accessed DCN. The default DCN may be preconfigured by the MME/SGSNfor the RAN node, and then the RAN node sends information about thedefault DCN to the UE by using an RRC connection setup. Alternatively,the UE may send an access termination request to the RAN node, toterminate this connection request process. Alternatively, the UE mayperform a process such as PLMN reselection and/or cell reselection, andobtain the first DCN information from another RAN node.

S706: The UE requests, to the RAN node, to establish a wirelessconnection.

A principle of S706 is similar to that of S605, and details are notdescribed herein again.

S707: The UE sends the DCN ID of the to-be-accessed DCN to the RAN node.

A principle of S707 is similar to that of S506, and details are notdescribed herein again.

S708: The RAN node determines, according to the DCN ID of theto-be-accessed DCN and the second DCN information, a DCN function entitygroup identifier corresponding to the DCN ID of the to-be-accessed DCN.

A principle of S708 is similar to that of S507, and details are notdescribed herein again.

S709: The RAN node determines the MME/SGSN according to the DCN functionentity group identifier and a second preset rule.

A principle of S709 is similar to that of S407, and details are notdescribed herein again.

S710: The RAN node initiates a service request to the MME/SGSN.

S711: The UE, the RAN node, the MME/SGSN, and the HSS together completeservice processing.

Principles of S710 and S711 are similar to those of S408 and S409, anddetails are not described herein again.

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 8 is a flowchart of an eighth embodiment of a core networkselection method according to the present invention. As shown in FIG. 8,the method in this embodiment is applicable to a communications systemincluding UE, a RAN node, a C-SGN, and a P-GW/an AS. The C-SGN is theforegoing core network device, and the P-GW/AS is a core network devicethat provides a core network user plane function. It should be notedthat the method in this embodiment may be applicable to anycommunications system that includes UE, an access network device, and acore network device. For ease of method embodiment description, theforegoing communications system is merely an example. The method in thisembodiment may include the following steps.

S801: The UE sends a first message to the RAN node, where the firstmessage includes a type of a to-be-accessed DCN selected by the UE.

The UE sends an RRC connection request to the RAN node, where the RRCconnection request includes information that DCN type=CIoT. The RRCconnection request further carries application-layer small data. Theapplication-layer small data may be encapsulated into a NAS message.

S802: The RAN node determines, according to the type of theto-be-accessed DCN and second DCN information, a DCN function entitygroup identifier corresponding to the type of the to-be-accessed DCN.

The RAN node determines, according to DCN type=CIoT and informationabout mapping between a DCN type and a DCN function entity groupidentifier, the DCN function entity group identifier corresponding tothe to-be-accessed DCN whose DCN type=CIoT. If the mapping informationincludes no DCN function entity group identifier corresponding to DCNtype=CIoT, the RAN node may select a default DCN or send an RRCconnection reject message (RRC Connection Reject) to the UE, where theRRC connection reject carries a reject cause “no DCN available (No DCNavailable)”, and the RAN node does not perform any subsequent step.

S803: The RAN node determines the C-SGN according to the DCN functionentity group identifier and a second preset rule.

The RAN node further selects one function entity, such as an MME in 4Gor an SGSN in 3G, in the DCN corresponding to the DCN function entitygroup identifier, as the core network device.

S804: The RAN node initiates a service request to the C-SGN.

S805: The UE, the RAN node, the C-SGN, and the P-GW/AS together completeservice processing.

The RAN node extracts a NAS message into which the application-layersmall data is encapsulated in the RRC connection request message, andsends the NAS message to the C-SGN. The C-SGN sends theapplication-layer small data to the packet data network gateway (PacketData Network Gateway, P-GW for short) or the application server(Application Server, AS for short).

According to this embodiment, UE selects a to-be-accessed DCN accordingto a service type of the UE, so as to implement accurate selection of acore network device by an access network device, improve accuracy of DCNselection by the access network device, avoid a communication signalingincrease and a processing delay in a DCN reselection process, andimprove communication efficiency.

FIG. 9 is a flowchart of a ninth embodiment of a core network selectionmethod according to the present invention. As shown in FIG. 9, themethod in this embodiment is applicable to a communications systemincluding an access network device and a core network device. The methodin this embodiment may include the following steps.

S901: The core network device receives a fifth message sent by theaccess network device, where the fifth message is used to indicate a DCNselection capability of the access network device or to request thesecond DCN information.

The fifth message is an S1 setup request message (S1 Setup Request) oran uplink information exchange request message (Uplink InformationExchange Request).

S902: The core network device sends a sixth message to the accessnetwork device, where the sixth message includes the second DCNinformation.

The sixth message is an S1 setup response message (S1 Setup Response) oran uplink information exchange response message (Uplink InformationExchange Response).

FIG. 10 is a flowchart of a tenth embodiment of a core network selectionmethod according to the present invention. As shown in FIG. 10, themethod in this embodiment is applicable to a communications systemincluding an access network device and a core network device. The methodin this embodiment may include the following steps.

S1001: The core network device sends a seventh message to the accessnetwork device, where the seventh message includes the second DCNinformation.

The seventh message is a mobility management entity MME configurationupdate message (MME Configuration Update) or an information transferindication message (Information Transfer Indication).

S1002: The core network device receives a message confirmation responsemessage that is sent by the access network device according to theseventh message.

The message confirmation response message may be an MME configurationupdate acknowledgement response (MME Configuration Update Acknowledge)or an information transfer confirmation (Information TransferConfirmation).

FIG. 11 is a schematic structural diagram of an embodiment of UEaccording to the present invention. As shown in FIG. 11, the apparatusin this embodiment may include a receiving module 11, a selection module12, and a sending module 13. The receiving module 11 is configured toobtain first dedicated core network DCN information from an accessnetwork device, where the first DCN information includes informationabout at least one DCN that can be accessed by the access networkdevice. The selection module 12 is configured to select a to-be-accessedDCN from the at least one DCN according to the first DCN information.The sending module 13 is configured to send information about theto-be-accessed DCN to the access network device, so that the accessnetwork device determines a core network device according to theinformation about the to-be-accessed DCN.

The apparatus in this embodiment may be configured to implement thetechnical solution in any one of the method embodiments in FIG. 1 andFIG. 4 to FIG. 8. Implementation principles and technical effects of theapparatus are similar to those in the method embodiments in FIG. 1 andFIG. 4 to FIG. 8, and details are not described herein again.

Further, the first DCN information includes a type of the at least oneDCN. The selection module 12 is specifically configured to select, fromthe at least one DCN, a DCN whose type matches a service type of theuser equipment UE, as the to-be-accessed DCN. The sending module 13 isspecifically configured to send the type of the to-be-accessed DCN tothe access network device, so that the access network device determinesthe core network device according to the type of the to-be-accessed DCN.

Further, the first DCN information includes a type, a DCN identity ID,and a priority of the at least one DCN. The selection module 12 isspecifically configured to: select, from the at least one DCN, one ormore DCNs whose types match a service type of the UE; and when a type ofone DCN matches the service type, determine the one DCN as theto-be-accessed DCN; or when types of multiple DCNs match the servicetype, select the to-be-accessed DCN from the multiple DCNs according tothe priority. The sending module 13 is specifically configured to send aDCN ID of the to-be-accessed DCN to the access network device, so thatthe access network device determines the core network device accordingto the DCN ID of the to-be-accessed DCN.

Further, the sending module 13 is further configured to send a firstmessage to the access network device, where the first message is used toindicate a DCN selection capability of the UE. The receiving module 11is specifically configured to receive a second message that is sent bythe access network device according to the first message, where thesecond message includes the first DCN information.

Further, the first DCN information includes a type of the at least oneDCN. The selection module 12 is specifically configured to determine ato-be-accessed public land mobile network PLMN according to a firstpreset rule, and select, from at least one DCN supported by theto-be-accessed PLMN, a DCN whose type matches a service type of the UE,as the to-be-accessed DCN. The sending module 13 is specificallyconfigured to send the type of the to-be-accessed DCN to the accessnetwork device, so that the access network device determines the corenetwork device according to the type of the to-be-accessed DCN.

Further, the first DCN information includes a type of the at least oneDCN. The selection module 12 is specifically configured to select, fromthe at least one DCN, a DCN whose type matches a service type of the UE,as the to-be-accessed DCN, and determine a to-be-accessed PLMN accordingto the type of the to-be-accessed DCN. The sending module 13 isspecifically configured to send the type of the to-be-accessed DCN tothe access network device, so that the access network device determinesthe core network device according to the type of the to-be-accessed DCN.

Further, the first DCN information includes a type, a DCN ID, and apriority of the at least one DCN. The selection module 12 isspecifically configured to: determine a to-be-accessed PLMN according toa first preset rule; select, from at least one DCN supported by theto-be-accessed PLMN, one or more DCNs whose types match a service typeof the UE; and when a type of one DCN matches the service type,determine the one DCN as the to-be-accessed DCN; or when types ofmultiple DCNs match the service type, select the to-be-accessed DCN fromthe multiple DCNs according to the priority. The sending module 13 isspecifically configured to send a DCN ID of the to-be-accessed DCN tothe access network device, so that the access network device determinesthe core network device according to the DCN ID of the to-be-accessedDCN.

Further, the first DCN information includes a type, a DCN ID, and apriority of the at least one DCN. The selection module 12 isspecifically configured to select, from the at least one DCN, a DCNwhose type matches a service type of the UE, determine a to-be-accessedPLMN according to the type of the DCN whose type matches the servicetype of the UE, and select, according to the priority and from at leastone DCN supported by the to-be-accessed PLMN, a DCN with the highestpriority as the to-be-accessed DCN. The sending module 13 isspecifically configured to send a DCN ID of the to-be-accessed DCN tothe access network device, so that the access network device determinesthe core network device according to the DCN ID of the to-be-accessedDCN.

Further, the receiving module 11 is specifically configured to receive athird message sent by the access network device, where the third messageincludes the first DCN information.

Further, the sending module 13 is further configured to request, to theaccess network device, to establish a wireless connection.

Further, the selection module 12 is further configured to: select apreset default DCN as the to-be-accessed DCN when the at least one DCNincludes no DCN whose type matches the service type; or send an accesstermination request to the access network device when the at least oneDCN includes no DCN whose type matches the service type; or obtain thefirst DCN information from another access network device when the atleast one DCN includes no DCN whose type matches the service type.

FIG. 12 is a schematic structural diagram of an embodiment of an accessnetwork device according to the present invention. As shown in FIG. 12,the apparatus in this embodiment may include a sending module 21, areceiving module 22, and a determining module 23. The sending module 21is configured to send first dedicated core network DCN information touser equipment UE, so that the UE selects a to-be-accessed DCN accordingto the first DCN information, where the first DCN information includesinformation about at least one DCN that can be accessed by the accessnetwork device. The receiving module 22 is configured to receiveinformation about the to-be-accessed DCN sent by the UE. The determiningmodule 23 is configured to determine a core network device according tothe information about the to-be-accessed DCN and preconfigured secondDCN information, and initiate a service request to the core networkdevice.

The apparatus in this embodiment may be configured to implement thetechnical solution in any one of the method embodiments in FIG. 2 andFIG. 4 to FIG. 10. Implementation principles and technical effects ofthe apparatus are similar to those in the method embodiments in FIG. 2and FIG. 4 to FIG. 10, and details are not described herein again.

Further, the information about the to-be-accessed DCN includes a type ofthe to-be-accessed DCN. The determining module 23 is specificallyconfigured to determine, according to the type of the to-be-accessed DCNand the second DCN information, a DCN function entity group identifiercorresponding to the type of the to-be-accessed DCN, and determine thecore network device according to the DCN function entity groupidentifier and a second preset rule.

Further, the determining module 23 is further configured to: determine apreset default core network device as the core network device when noDCN function entity group identifier corresponding to the type of theto-be-accessed DCN is determined according to the type of theto-be-accessed DCN and the second DCN information; or send a fourthmessage to the UE when no DCN function entity group identifiercorresponding to the type of the to-be-accessed DCN is determinedaccording to the type of the to-be-accessed DCN and the second DCNinformation, where the fourth message is used to terminate an accessrequest.

Further, the information about the to-be-accessed DCN includes a DCN IDof the to-be-accessed DCN. The determining module 23 is specificallyconfigured to determine, according to the DCN ID of the to-be-accessedDCN and the second DCN information, a DCN function entity groupidentifier corresponding to the to-be-accessed DCN, and determine thecore network device according to the DCN function entity groupidentifier and a second preset rule.

Further, the determining module 23 is further configured to: determine apreset default core network device as the core network device when noDCN function entity group identifier corresponding to the DCN ID of theto-be-accessed DCN is determined according to the DCN ID of theto-be-accessed DCN and the second DCN information; or send a fourthmessage to the UE when no DCN function entity group identifiercorresponding to the DCN ID of the to-be-accessed DCN is determinedaccording to the DCN ID of the to-be-accessed DCN and the second DCNinformation, where the fourth message is used to terminate an accessrequest.

Further, the receiving module 22 is further configured to obtain thesecond DCN information from the core network device, where the secondDCN information includes a type and a DCN function entity groupidentifier of the at least one DCN.

Further, the second DCN information further includes a DCN ID and apriority of the at least one DCN.

Further, the receiving module 22 is further configured to receive afirst message sent by the UE, where the first message is used toindicate a DCN selection capability of the UE. The sending module 21 isspecifically configured to send a second message to the UE according tothe first message, where the second message includes the first DCNinformation.

Further, the sending module 21 is specifically configured to send athird message to the UE, where the third message includes the first DCNinformation.

FIG. 13 is a schematic structural diagram of an embodiment of a corenetwork device according to the present invention. As shown in FIG. 13,the apparatus in this embodiment may include a sending module 31 and aprocessing module 32. The sending module 31 is configured to send seconddedicated core network DCN information to an access network device, sothat the access network device determines the core network deviceaccording to the second DCN information. The processing module 32 isconfigured to process a service request initiated by the access networkdevice.

The apparatus in this embodiment may be configured to implement thetechnical solution in any one of the method embodiments in FIG. 3 andFIG. 4 to FIG. 10. Implementation principles and technical effects ofthe apparatus are similar to those in the method embodiments in FIG. 3and FIG. 4 to FIG. 10, and details are not described herein again.

Further, the second DCN information includes a type and a DCN functionentity group identifier of at least one DCN.

Further, the second DCN information further includes a DCN ID and apriority of the at least one DCN.

FIG. 14 is a schematic structural diagram of another embodiment of UEaccording to the present invention. As shown in FIG. 14, the apparatusin this embodiment may include a receiver 41, a processor 42, and atransmitter 43. The receiver 41 is configured to obtain first dedicatedcore network DCN information from an access network device, where thefirst DCN information includes information about at least one DCN thatcan be accessed by the access network device. The processor 42 isconfigured to select a to-be-accessed DCN from the at least one DCNaccording to the first DCN information. The transmitter 43 is configuredto send information about the to-be-accessed DCN to the access networkdevice, so that the access network device determines a core networkdevice according to the information about the to-be-accessed DCN.

The apparatus in this embodiment may be configured to implement thetechnical solution in any one of the method embodiments in FIG. 1 andFIG. 4 to FIG. 8. Implementation principles and technical effects of theapparatus are similar to those in the method embodiments in FIG. 1 andFIG. 4 to FIG. 8, and details are not described herein again.

Further, the first DCN information includes a type of the at least oneDCN. The processor 42 is specifically configured to select, from the atleast one DCN, a DCN whose type matches a service type of the userequipment UE, as the to-be-accessed DCN. The transmitter 43 isspecifically configured to send the type of the to-be-accessed DCN tothe access network device, so that the access network device determinesthe core network device according to the type of the to-be-accessed DCN.

Further, the first DCN information includes a type, a DCN identity ID,and a priority of the at least one DCN. The processor 42 is specificallyconfigured to: select, from the at least one DCN, one or more DCNs whosetypes match a service type of the UE; and when a type of one DCN matchesthe service type, determine the one DCN as the to-be-accessed DCN; orwhen types of multiple DCNs match the service type, select theto-be-accessed DCN from the multiple DCNs according to the priority. Thetransmitter 43 is specifically configured to send a DCN ID of theto-be-accessed DCN to the access network device, so that the accessnetwork device determines the core network device according to the DCNID of the to-be-accessed DCN.

Further, the transmitter 43 is further configured to send a firstmessage to the access network device, where the first message is used toindicate a DCN selection capability of the UE. The receiver 41 isspecifically configured to receive a second message that is sent by theaccess network device according to the first message, where the secondmessage includes the first DCN information.

Further, the first DCN information includes a type of the at least oneDCN. The processor 42 is specifically configured to determine ato-be-accessed public land mobile network PLMN according to a firstpreset rule, and select, from at least one DCN supported by theto-be-accessed PLMN, a DCN whose type matches a service type of the UE,as the to-be-accessed DCN. The transmitter 43 is specifically configuredto send the type of the to-be-accessed DCN to the access network device,so that the access network device determines the core network deviceaccording to the type of the to-be-accessed DCN.

Further, the first DCN information includes a type of the at least oneDCN. The processor 42 is specifically configured to select, from the atleast one DCN, a DCN whose type matches a service type of the UE, as theto-be-accessed DCN, and determine a to-be-accessed PLMN according to thetype of the to-be-accessed DCN. The transmitter 43 is specificallyconfigured to send the type of the to-be-accessed DCN to the accessnetwork device, so that the access network device determines the corenetwork device according to the type of the to-be-accessed DCN.

Further, the first DCN information includes a type, a DCN ID, and apriority of the at least one DCN. The processor 42 is specificallyconfigured to: determine a to-be-accessed PLMN according to a firstpreset rule; select, from at least one DCN supported by theto-be-accessed PLMN, one or more DCNs whose types match a service typeof the UE; and when a type of one DCN matches the service type,determine the one DCN as the to-be-accessed DCN; or when types ofmultiple DCNs match the service type, select the to-be-accessed DCN fromthe multiple DCNs according to the priority. The transmitter 43 isspecifically configured to send a DCN ID of the to-be-accessed DCN tothe access network device, so that the access network device determinesthe core network device according to the DCN ID of the to-be-accessedDCN.

Further, the first DCN information includes a type, a DCN ID, and apriority of the at least one DCN. The processor 42 is specificallyconfigured to select, from the at least one DCN, a DCN whose typematches a service type of the UE, determine a to-be-accessed PLMNaccording to the type of the DCN whose type matches the service type ofthe UE, and select, according to the priority and from at least one DCNsupported by the to-be-accessed PLMN, a DCN with the highest priority asthe to-be-accessed DCN. The transmitter 43 is specifically configured tosend a DCN ID of the to-be-accessed DCN to the access network device, sothat the access network device determines the core network deviceaccording to the DCN ID of the to-be-accessed DCN.

Further, the receiver 41 is specifically configured to receive a thirdmessage sent by the access network device, where the third messageincludes the first DCN information.

Further, the transmitter 43 is further configured to request, to theaccess network device, to establish a wireless connection.

Further, the processor 42 is further configured to: select a presetdefault DCN as the to-be-accessed DCN when the at least one DCN includesno DCN whose type matches the service type; or send an accesstermination request to the access network device when the at least oneDCN includes no DCN whose type matches the service type; or obtain thefirst DCN information from another access network device when the atleast one DCN includes no DCN whose type matches the service type.

FIG. 15 is a schematic structural diagram of another embodiment of anaccess network device according to the present invention. As shown inFIG. 15, the apparatus in this embodiment may include a transmitter 51,a receiver 52, and a processor 53. The transmitter 51 is configured tosend first dedicated core network DCN information to user equipment UE,so that the UE selects a to-be-accessed DCN according to the first DCNinformation, where the first DCN information includes information aboutat least one DCN that can be accessed by the access network device. Thereceiver 52 is configured to receive information about theto-be-accessed DCN sent by the UE. The processor 53 is configured todetermine a core network device according to the information about theto-be-accessed DCN and preconfigured second DCN information, andinitiate a service request to the core network device.

The apparatus in this embodiment may be configured to implement thetechnical solution in any one of the method embodiments in FIG. 2 andFIG. 4 to FIG. 10. Implementation principles and technical effects ofthe apparatus are similar to those in the method embodiments in FIG. 2and FIG. 4 to FIG. 10, and details are not described herein again.

Further, the information about the to-be-accessed DCN includes a type ofthe to-be-accessed DCN. The processor 53 is specifically configured todetermine, according to the type of the to-be-accessed DCN and thesecond DCN information, a DCN function entity group identifiercorresponding to the type of the to-be-accessed DCN, and determine thecore network device according to the DCN function entity groupidentifier and a second preset rule.

Further, the processor 53 is further configured to: determine a presetdefault core network device as the core network device when no DCNfunction entity group identifier corresponding to the type of theto-be-accessed DCN is determined according to the type of theto-be-accessed DCN and the second DCN information; or send a fourthmessage to the UE when no DCN function entity group identifiercorresponding to the type of the to-be-accessed DCN is determinedaccording to the type of the to-be-accessed DCN and the second DCNinformation, where the fourth message is used to terminate an accessrequest.

Further, the information about the to-be-accessed DCN includes a DCN IDof the to-be-accessed DCN. The processor 53 is specifically configuredto determine, according to the DCN ID of the to-be-accessed DCN and thesecond DCN information, a DCN function entity group identifiercorresponding to the to-be-accessed DCN, and determine the core networkdevice according to the DCN function entity group identifier and asecond preset rule.

Further, the processor 53 is further configured to: determine a presetdefault core network device as the core network device when no DCNfunction entity group identifier corresponding to the DCN ID of theto-be-accessed DCN is determined according to the DCN ID of theto-be-accessed DCN and the second DCN information; or send a fourthmessage to the UE when no DCN function entity group identifiercorresponding to the DCN ID of the to-be-accessed DCN is determinedaccording to the DCN ID of the to-be-accessed DCN and the second DCNinformation, where the fourth message is used to terminate an accessrequest.

Further, the receiver 52 is further configured to obtain the second DCNinformation from the core network device, where the second DCNinformation includes a type and a DCN function entity group identifierof the at least one DCN.

Further, the second DCN information further includes a DCN ID and apriority of the at least one DCN.

Further, the receiver 52 is further configured to receive a firstmessage sent by the UE, where the first message is used to indicate aDCN selection capability of the UE. The transmitter 51 is specificallyconfigured to send a second message to the UE according to the firstmessage, where the second message includes the first DCN information.

Further, the transmitter 51 is specifically configured to send a thirdmessage to the UE, where the third message includes the first DCNinformation.

FIG. 16 is a schematic structural diagram of another embodiment of acore network device according to the present invention. As shown in FIG.16, the apparatus in this embodiment may include a transmitter 61 and aprocessor 62. The transmitter 61 is configured to send second dedicatedcore network DCN information to an access network device, so that theaccess network device determines the core network device according tothe second DCN information. The processor 62 is configured to process aservice request initiated by the access network device.

The apparatus in this embodiment may be configured to implement thetechnical solution in any one of the method embodiments in FIG. 3 andFIG. 4 to FIG. 10. Implementation principles and technical effects ofthe apparatus are similar to those in the method embodiments in FIG. 3and FIG. 4 to FIG. 10, and details are not described herein again.

Further, the second DCN information includes a type and a DCN functionentity group identifier of at least one DCN.

Further, the second DCN information further includes a DCN ID and apriority of the at least one DCN.

FIG. 17 is a schematic structural diagram of an embodiment of acommunications system according to the present invention. As shown inFIG. 17, the system in this embodiment includes UE 71, an access networkdevice 72, and a core network device 73. The UE 71 may use a structurein the apparatus embodiment shown in FIG. 11. Correspondingly, the UE 71may implement the technical solution in any one of the methodembodiments in FIG. 1 and FIG. 4 to FIG. 8. Implementation principlesand technical effects of the UE 71 are similar to those in the methodembodiments in FIG. 1 and FIG. 4 to FIG. 8, and details are notdescribed herein again. The access network device 72 may use a structurein the apparatus embodiment shown in FIG. 12. Correspondingly, theaccess network device 72 may implement the technical solution in any oneof the method embodiments in FIG. 2 and FIG. 4 to FIG. 10.Implementation principles and technical effects of the access networkdevice 72 are similar to those in the method embodiments in FIG. 2 andFIG. 4 to FIG. 10, and details are not described herein again. The corenetwork device 73 may use a structure in the apparatus embodiment shownin FIG. 13. Correspondingly, the core network device 73 may implementthe technical solution in any one of the method embodiments in FIG. 3and FIG. 4 to FIG. 10. Implementation principles and technical effectsof the core network device 73 are similar to those in the methodembodiments in FIG. 3 and FIG. 4 to FIG. 10, and details are notdescribed herein again.

Further, the UE 71 in the system structure shown in FIG. 17 may use astructure in the apparatus embodiment shown in FIG. 14. Correspondingly,the UE 71 may implement the technical solution in any one of the methodembodiments in FIG. 1 and FIG. 4 to FIG. 8. Implementation principlesand technical effects of the UE 71 are similar to those in the methodembodiments in FIG. 1 and FIG. 4 to FIG. 8, and details are notdescribed herein again. The access network device 72 may use a structurein the apparatus embodiment shown in FIG. 15. Correspondingly, theaccess network device 72 may implement the technical solution in any oneof the method embodiments in FIG. 2 and FIG. 4 to FIG. 10.Implementation principles and technical effects of the access networkdevice 72 are similar to those in the method embodiments in FIG. 2 andFIG. 4 to FIG. 10, and details are not described herein again. The corenetwork device 73 may use a structure in the apparatus embodiment shownin FIG. 16. Correspondingly, the core network device 73 may implementthe technical solution in any one of the method embodiments in FIG. 3and FIG. 4 to FIG. 10. Implementation principles and technical effectsof the core network device 73 are similar to those in the methodembodiments in FIG. 3 and FIG. 4 to FIG. 10, and details are notdescribed herein again.

In the several embodiments provided in the present invention, it shouldbe understood that the disclosed apparatus and method may be implementedin other manners. For example, the described apparatus embodiment ismerely an example. For example, the unit division is merely logicalfunction division and may be other division in actual implementation.For example, multiple units or components may be combined or may beintegrated into another system, or some features may be ignored or notperformed. In addition, the displayed or discussed mutual couplings ordirect couplings or communication connections may be implemented byusing some interfaces. The indirect couplings or communicationconnections between the apparatuses or units may be implemented inelectrical, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on multiplenetwork units. Some or all of the units may be selected according toactual needs, to achieve the objectives of the solutions in theembodiments.

In addition, functional units in the embodiments of the presentinvention may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units may be integratedinto one unit. The integrated unit may be implemented in a form ofhardware, or may be implemented in a form of hardware in addition to asoftware function unit.

When the foregoing integrated unit is implemented in the form of asoftware function unit, the integrated unit may be stored in acomputer-readable storage medium. The software function unit is storedin a storage medium and includes several instructions for instructing acomputer device (which may be a personal computer, a server, a networkdevice, or the like) or a processor (processor) to perform a part of thesteps of the methods described in the embodiments of the presentinvention. The foregoing storage medium includes any medium that canstore program code, such as a USB flash drive, a removable hard disk, aread-only memory (Read-Only Memory, ROM), a random access memory (RandomAccess Memory, RAM), a magnetic disk, or an optical disc.

It may be clearly understood by persons skilled in the art that, forconvenience and briefness of description, only the division of theforegoing function modules is used as an example for illustration. Inactual application, the foregoing functions may be allocated, accordingto a need, to different function modules for implementation. That is, aninner structure of an apparatus is divided into different functionmodules, to implement all or a part of the functions described above.For a specific working process of the foregoing apparatus, refer to acorresponding process in the foregoing method embodiments, and detailsare not described herein again.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions in the presentinvention, but are not intended for limiting the present invention.Although the present invention is described in detail with reference tothe foregoing embodiments, persons of ordinary skill in the art shouldunderstand that they may still make modifications to the technicalsolutions described in the foregoing embodiments or make equivalentreplacements to some or all technical features thereof, withoutdeparting from the scope of the technical solutions in the embodimentsof the present invention.

What is claimed:
 1. A method, implemented by user equipment, comprising:determining first information about a first network slice that the userequipment wishes to access, wherein the first information comprises atype of the first network slice, wherein when the user equipment hassecond information comprising at least one network slice type obtainedfrom a network device, the first information comprises the secondinformation or a subset of the second information, and wherein when theuser equipment does not have the second information, the firstinformation comprises a default configured information or a subset ofthe default configured information; and sending the first information toan access network device.
 2. The method according to claim 1, whereinthe first information is used for determination of a core networkdevice.
 3. The method according to claim 1, wherein a public land mobilenetwork (PLMN) that the user equipment wishes to access supports thefirst network slice.
 4. The method according to claim 1, wherein thefirst information further comprises: information for differentiatingmultiple network slices with same type.
 5. The method according to claim1, wherein the default configured information is associated with apublic land mobile network (PLMN).
 6. The method according to claim 1,wherein the type of the first network slice matches a service that theuser equipment wishes to use.
 7. The method according to claim 1,wherein the method further comprises: requesting, to the access networkdevice, to establish a wireless connection.
 8. The method according toclaim 1, wherein the second information comprises allowed informationfrom the network device or configured information from the networkdevice.
 9. A user equipment, comprising at least one processer; and amemory configured to store program code, wherein the at least oneprocesser is configured to run the program code, causing the userequipment to execute the steps of: determining first information about afirst network slice that the user equipment wishes to access, whereinthe first information comprises a type of the first network slice,wherein when the user equipment has second information comprising atleast one network slice type obtained from a network device, the firstinformation comprises the second information or a subset of the secondinformation, and wherein when the user equipment does not have thesecond information, the first information comprises a default configuredinformation or a subset of the default configured information; andsending the first information to an access network device.
 10. The userequipment according to claim 9, wherein the first information is usedfor determination of a core network device.
 11. The user equipmentaccording to claim 9, wherein a public land mobile network (PLMN) thatthe apparatus wishes to access supports the first network slice.
 12. Theuser equipment according to claim 9, wherein the type of the firstnetwork slice matches a service that the user equipment wishes to use.13. A non-transitory computer-readable medium storing computerinstructions for a computer or mobile device, that when the computerinstructions are executed by one or more processors, cause the one ormore processors to perform the steps of: determining first informationabout a first network slice that the user equipment wishes to access,wherein the first information comprises a type of the first networkslice, wherein when the user equipment has second information comprisingat least one network slice type obtained from a network device, thefirst information comprises the second information or a subset of thesecond information, and wherein when the user equipment does not havethe second information, the first information comprises a defaultconfigured information or a subset of the default configuredinformation; and sending the first information to an access networkdevice wherein.
 14. The non-transitory computer-readable mediumaccording to claim 13, wherein the first information further comprises:information for differentiating multiple network slices with same type.15. The non-transitory computer-readable medium according to claim 13,wherein the default configured information is associated with a publicland mobile network (PLMN).
 16. The non-transitory computer-readablemedium according to claim 13, wherein the type of the first networkslice matches a service that the user equipment wishes to use.
 17. Thenon-transitory computer-readable medium according to claim 13, whereinthe first information comprises the default configured information orthe subset of the default configured information, and the determiningthe first information comprises: obtaining the second information fromthe network device, wherein the second information comprises at leastone network slice type; and determining the first information tocomprise the default configured information in response to each of theat least one network slice type not matching a service that the userequipment wishes to use or in response to a public land mobile network(PLMN) that the user equipment wishes to access not supporting each ofthe at least one network slice type.